The present invention relates generally to a process for manufacturing a multilayer composite acoustical and thermal insulator which may be utilized to insulate an environment such as a passenger compartment of a vehicle from the heat and sound generated by mechanical components of that vehicle during its operation.
It is well known in the art to provide acoustical and thermal insulators on an automobile, truck or other vehicle in an effort to protect and insulate the operating or passenger compartment from the noise and heat generated by the mechanical equipment of the associated vehicle. Toward this end, mats of high temperature glass fibers have been utilized, eg. (a) on the fire wall between the dashboard and engine compartment and (b) along the floor pan of the vehicle between the passenger compartment and the drive line and exhaust system. These materials provide heat insulation which makes it possible to maintain cooler and more comfortable temperatures in the operator/passenger compartment particularly during the summer months. Additionally, these materials provide needed sound insulation, reducing or eliminating various mechanical sounds of the motor, drive train as well as the suspension and tires as the vehicle travels over the often rough and bumpy surface of the roadway.
Various methods of manufacturing or fabricating such acoustical and thermal insulators are known in the art. Examples of these methods are found in, for example, U.S. Pat. No. 3,752,062 to Hubert et al. and U.S. Pat. No. 4,579,764 to Peoples, Jr. et al. In the Hubert et al. patent, thin, thermoplastic resin-coated sheets of fibrous materials are molded in a press by (1) heating the platens while the material is loaded therein, (2) compressing and molding the material and (3) cooling the platens to set the material in the desired shape prior to opening the platens and removing the part. In the Peoples, Jr. et al. patent, a carpet assembly is provided including a moldable thermoplastic polymer layer and a sound deadening foam cushion. The carpet assembly is preheated to temperatures sufficiently high to soften the thermoplastic layer. The preheated carpet assembly is then placed in cooperating mold dies and pressure is applied in order to mold the carpet assembly into the desired configuration. After sufficient cooling is provided to set the carpet assembly in the desire shape, the mold dies are opened and the molded carpet assembly is removed from the mold.
The Hubert et al. patent teaches that it is possible to mold thermoplastic resin coated sheets of fibrous material by heating and cooling those sheets during the time they are held in the mold. Thermoplastic resin-coated sheets of fibrous material are useful for certain applications but for most applications and particularly those relating to the insulation of automobiles, such sheets do not always provide the desired acoustical and thermal insulation properties. Multilayer composite insulators allow one to tailor the characteristics of the insulator to better meet the particular needs of an application. The Hubert et al. patent, however, fails to indicate that the hot/cold mold technique may be utilized to manufacture such multilayer composite insulators.
The Peoples, Jr. et al. patent teaches a transfer mold technique for the manufacturing of a carpet assembly including a thermoplastic polymer layer and a sound deadening foam cushion. There, however, is no indication in this reference that the transfer mold technique may be utilized in the manufacturing/fabricating of a multilayer composite insulator with enhanced acoustical and thermal insulating properties of the nature described below.
In accordance with the purposes of the present invention as described herein, an improved process is provided for forming a multilayer composite insulator. Such an insulator may be used for various applications in the acoustical and/or thermal insulation of vehicles, appliances such as dishwashers, clothes driers, refrigerators and freezers, as well as in the building industry. The process includes the steps of forming an insulator precursor by orienting an insulation insert in a desired location between a first facing layer and a layer of a polymer based blanket material enclosing the insulator precursor in a molding press. This is followed by the heating of the insulator precursor in the molding press to a temperature sufficiently high to soften polymer binding fiber in the polymer based blanket material and thereby causing reshaping/molding of the insulator precursor. Next is the cooling of the insulator precursor in the molding press so as to set the insulator precursor in its molded shape and complete formation of the insulator. This is then followed by the opening of the molding press and the removing of the insulator.
The insulator precursor may be formed in a continuous operation from continuous webs of facing layer (eg. heat reflective) material and polymer based blanket material. Alternatively, the process may include the step of cutting the first facing layer and the polymer based blanket material as well as the insulation insert to desired dimensions prior to forming.
More specifically describing the invention, the beating of the insulator precursor is typically completed to a temperature between approximately 200-400xc2x0 F. and more typically to a temperature between 300-375xc2x0 F.
During processing, the molding press is utilized to apply pressure to the insulator precursor at a level of between approximately 0.5-100.0 psi for approximately 10-90 seconds and more preferably 15-45 seconds dwell time. Further, the method includes the compressing of the insulator precursor between approximately 10-95% and more typically 50-90% when applying the pressure in order to complete the molding process.
Still further, the process may include the step of orienting an additional or second facing layer with the insulation insert, the first facing layer and the polymer based blanket material layer when forming the insulator precursor. In this approach, a four layer composite insulator results.
In accordance with yet another aspect of the present invention, the process for forming a multilayer composite insulator comprises the steps of forming an insulator precursor by orienting an insulation insert in a desired location between a first facing layer and a layer of a polymer based blanket material and preheating that insulator precursor to a temperature sufficiently high to soften the polymer binding fiber in the polymer based blanket material. This is followed by the transferring of the preheated insulator precursor to a molding press while the polymer binding fibers of the polymer based blanket material remain softened. Next is the closing of the insulator precursor in a molding press. This is followed by the cooling of the insulator precursor in the molding press so as to set the insulator precursor in its molded shape and complete formation of the insulator. Finally, the process includes the opening of the molding press and the removing of the insulator.
As noted above, the process just described may be completed as a continuous operation from continuous rolls of starting material or each of the materials may be cut to desired dimension prior to processing.
More specifically describing this process, the preheating of the insulator precursor is typically to a temperature between approximately 220-425xc2x0 F. and more typically to a temperature between approximately 300-375xc2x0 F. When closed in the press, the insulator precursor is subjected to the application of pressure at a level between approximately 0.5-100.0 psi for approximately 10-90 seconds of dwell time. This pressure results in the compressing of the insulator precursor between approximately 10-95%.
As with the first processing embodiment, the second processing embodiment may also include the step of orienting a second facing layer with the insulation insert, the first facing layer and polymer based blanket layer when forming the insulator precursor. This allows the production of a four layer insulator with virtually any facing desired.
In accordance with yet another aspect and embodiment of the present invention, the process for forming a multilayer composite insulator comprises the steps of forming an insulator precursor by orienting an insulation insert in a desired location between a first facing layer and polymer based blanket material layer and providing a selected area of the polymer based blanket material having added thickness. This is followed by the heating of the insulator precursor in the molding press to a temperature sufficiently high to soften polymer binding fiber only in the selected area of the polymer based blanket material. This is followed by the cooling of the insulator precursor in the molding press so as to set the insulator precursor in its molded shape and complete formation of the insulator. Following cooling is the opening of the molding press and the removing of the insulator.
As with the other embodiments of the present process described above, this third embodiment may be completed as a continuous molding operation from continuous rolls of starting material or the process may include the step of cutting the starting materials to desired dimensions prior to forming.
In accordance with the steps already described above, heating of the insulator precursor in this third embodiment is typically completed to a temperature between 200-400xc2x0 F. and more typically between a temperature of approximately 300-375xc2x0 F. The process also includes the applying of pressure to the insulator precursor in the molding press at a level of between approximately 0.5-100.0 psi for a substantially 10-90 seconds. This is done in order to provide compressing of the insulator precursor between approximately 10-95% during the molding operation.
As noted above with the other embodiments of the present process, the third embodiment may also include the orienting of a second facing layer with the insulation insert, the first facing layer and the polymer based blanket layer when forming the insulator precursor. As noted above, this allows the formation of a four layer composite with a facing layer added to provide desired mechanical, physical and/or aesthetic properties.
The third embodiment may be more broadly defined as a process of molding a panel from a polymer based blanket material. That process may be described as comprising the steps of providing the polymer based blanket material with at least one selected area having additional thickness and molding the polymer based blanket material into desired shaped wherein the at least one selected area is characterized by relatively high density and a relatively increased rigidity.
More specifically, the process includes the heating of the polymer based blanket material to a temperature sufficiently high to soften the polymer binding fiber in the polymer based blanket material and applying pressure sufficient to form the polymer based blanket material into a desired panel shape.
Still other objects of the present invention will become apparent to those skilled in this art from the following description wherein there is shown and described a preferred embodiment of this invention, simply by way of illustration of one of the modes best suited to carry out the invention. As it will be realized, the invention is capable of other different embodiments and its several details are capable of modification in various, obvious aspects all without departing from the invention. Accordingly, the drawings and descriptions will be regarded s illustrative in nature and not as restrictive.